Wafer handling device and method for testing wafers

ABSTRACT

A wafer handling device comprises metrology equipment ( 410, 420, 430, 440, 450, 460 ) for testing selected wafers as well as a stationary wafer storage system ( 300 ). The stationary wafer storage system ( 300 ) has a buffer ( 310 ) to store wafers and a load-and-unload station ( 320 ) to transfer selected wafers between the buffer ( 310 ) and wafer transport means ( 330 ). The wafer transport means are provided for transferring selected wafers between the load-and-unload station ( 320 ) and the metrology equipment ( 410, 420, 430, 440, 450, 460 ).

FIELD OF THE INVENTION

[0001] The present invention generally relates to the field of semiconductor production, and more particularly to a wafer handling device and methods for testing wafers.

BACKGROUND OF THE INVENTION

[0002] Semiconductor wafers or other such substrates are typically subjected to many processing steps that involve moving said wafers from one type of processing tool to another. For example, wafers that have been subjected to one process in a wafer deposition chamber may have to be moved for cleaning and drying to another processing tool, and then they may have to be transferred to a different processing tool for additional processing steps. In many cases the wafers have to be stored between different processing steps. To ensure high quality standards it is necessary to test control and monitor wafers between different processing steps. However, it is complicated and expensive to perform these tests. This is for example due to the fact that the wafers to be tested usually are spread over many pods where they are stored. Therefore, it is logistically difficult to transport the wafers to be tested to the respective metrology equipment or between single test stations forming the metrology equipment.

[0003] The present invention seeks to provide a wafer handling device and a method for testing wafers reducing the logistical efforts for testing selected wafers, especially control and monitor wafers.

BRIEF DESCRIPTION OF THE DRAWING

[0004] The sole FIGURE is a schematic top view of a wafer handling device in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0005] In accordance with the present invention there is provided a wafer handling device, comprising metrology equipment 410, 420, 430, 440, 450, 460 for testing selected wafers and a stationary wafer storage system 300, said stationary wafer storage system 300 having a buffer 310 for storing a plurality of wafers and at least a load-and-unload station 320 for transferring said selected wafers between said buffer 310 and wafer transport means 330, wherein said wafer transport means are provided for transferring one or more of said selected wafers between said load-and-unload station 320 and said metrology equipment 410, 420, 430, 440, 450, 460.

[0006] The present invention further provides a method for testing wafers, said method comprising the following steps:

[0007] a) selecting wafers to be tested from a plurality of wafers stored in a stationary storage system 300;

[0008] b) transferring at least some of said wafers to be tested from said stationary storage system 300 to wafer transport means 330 via a load-and-unload station 320 assigned to said stationary storage system 300; and

[0009] c) transferring at least some of said wafers to be tested to metrology equipment 410, 420, 430, 440, 450, 460 by said wafer transport means 330 and performing at least one test step.

[0010] With both, the wafer handling device and the method for testing wafers in accordance with the present invention, it is easier to perform the necessary wafer testing since the logistical effort to transport the wafers to be tested from the actual storage place to the metrology equipment may be reduced.

[0011] The sole FIGURE shows a schematic top view of a wafer handling device in accordance with the present invention. A stationary storage system is designated with numeral 300 and comprises a buffer 310 for storing a few thousands of wafers, for example 1000, 5000 or 10000 wafers. Preferably the wafers are stored within pods in said buffer 310. These pods may for example be FOUPs (Front Opening Unified Pods) or SMIF (Standard Mechanical InterFace) boxes generally known in the art. The stationary storage system 300 further comprises a load-and-unload station 320. It is preferred that the stationary storage system 300 is capable of tracking single wafers and/or lots of wafers to provide a fast access, for example to wafers that have to be tested. With the embodiment of the FIGURE the wafer transport means are realized by robots 330. At least one of these robots 330 is able to interact with the load-and-unload station 320 to transfer one or more wafers that have to be tested. The robots 330 transport the wafers to be tested to metrology equipment and between single stations thereof. In accordance with the FIGURE, this metrology equipment comprises the following stations: a particle monitoring station 410, a stress test station 420, a thickness test station 430, an X-ray fluorescence analysis station and an atomic force microscopy station 440, an orienter and map station 450, and an opaque film thickness test station 460. The test stations 410, 420, and 430 form a first group 480, while the test stations 440, 450, and 460 form a second group 490. Preferably, the groups formed by different test stations are arranged adjacent to each other.

[0012] To each of the groups 480, 490 there is assigned a robot 330 for transferring the wafers between the corresponding test stations. For storing one or more wafers between different testing steps there are provided intermediate storage means 470. In accordance with the embodiment shown in the FIGURE these intermediate storage means 470 are realized by pods 470. The wafer handling device in accordance with the FIGURE provides a more optimal handling of single wafers or groups of wafers for metrology and a more optimal storage of test, calibration, and control wafers. Furthermore, the embodiment in accordance with the FIGURE provides a more optimal rooting of single wafers through different metrology steps.

[0013] While the invention has been described in terms of particular structures, devices and methods, those of skill in the art will understand, based on the description herein, that the invention is not limited merely to such examples and that the full scope of the invention is properly determined by the claims that follow. 

1. A wafer handling device, comprising: metrology equipment for testing selected wafers, and a stationary wafer storage system, said stationary wafer storage system having a buffer for storing a plurality of wafers and at least a load-and-unload station for transferring said selected wafers between said buffer and wafer transport means, wherein said wafer transport means are provided for transferring one or more of said selected wafers between said load-and-unload station and said metrology equipment.
 2. The wafer handling device according to claim 1, wherein said wafer transport means comprise at least one robot.
 3. The wafer handling device according to claim 1, wherein said metrology equipment comprises one or more of the following stations: a particle monitoring station, a stress test station, a thickness test station, an X-ray fluorescence analysis station, an atomic force microscopy station, an orienter station, a map station, and an opaque film thickness test station.
 4. The wafer handling device according to claim 1, wherein said metrology equipment comprises groups formed by different test stations arranged adjacent to each other.
 5. The wafer handling device according to claim 1, wherein said metrology equipment comprises groups formed by different test stations arranged adjacent to each other, wherein said wafer transport means comprise robots, and wherein to each of said groups there is assigned one of said robots.
 6. The wafer handling device according to claim 1, further comprising intermediate storage means for storing wafers between testing steps performed by said metrology equipment.
 7. The wafer handling device according to claim 1, further comprising intermediate storage means for storing wafers between test steps performed by said metrology equipment, wherein said intermediate storage means comprise one or more pods.
 8. The wafer handling device according to claim 1, wherein said wafers are stored in said buffer within pods.
 9. A method for testing wafers, comprising the following steps: a) selecting wafers to be tested from a plurality of wafers stored in a stationary storage system; b) transferring at least some of said wafers to be tested from said stationary storage system to wafer transport means via a load-and-unload station assigned to said stationary storage system; and c) transferring at least some of said wafers to be tested to metrology equipment by said wafer transport means and performing at least one test step.
 10. The method according to claim 9, further comprising the following steps: d) transferring at least some of said wafers to be tested between at least some of different test stations forming said metrology equipment, and performing at least one further test step; and e) transferring at least some of the wafers tested with step d) back to said load-and-unload station by said wafer transport means, for storing them in said stationary storage system.
 11. The method according to claim 9, wherein said step a) comprises selecting said wafers to be tested from different wafer lots.
 12. The method according to claim 9, wherein said metrology equipment comprises one ore more of the following stations: a particle monitoring station, a stress test station, a thickness test station, an X-ray fluorescence analysis station, an atomic force microscopy station, an orienter station, a map station, an opaque film thickness test station.
 13. The method according to claim 9, wherein said metrology equipment comprises groups formed by different test stations arranged adjacent to each other, wherein said wafer transport means comprise robots, and wherein to each of said groups there is assigned one of said robots.
 14. The method according to claim 9, wherein at least some of said wafers to be tested are stored in intermediate storage means between different test steps. 